1. Field of the Invention
This invention relates to a highway trailer entry guide for mounting on the left and right stiles of a building entranceway.
2. Prior Art
As is well-known, it is common practice to back highway trailers up to loading docks and load or unload the trailer through the open rear entranceway thereof. Commonly, this is accomplished by use of fork lift trucks. One problem which has been encountered in connection with such activity is proper alignment of the trailer entranceway with the building entranceway. The highway trailer may not be backed up exactly in proper alignment with the building entranceway. A more serious problem is encountered in connection with highway trailers when such trailers get older. Frequently, the trailer side walls lean to the left or to the right as a consequence of warping or as a result of being impacted by fixed structures during the course of use thereof.
When the side walls of the highway trailer are tilted, the upper portions of the side walls are not in alignment with the lower portions. The highway trailer is normally backed up to a loading dock with the lower portion of the trailer being aligned with the building entranceway. Thus, the upper portions of the trailer side walls may be tilted to the left or to the right with respect to the building entranceway. When it is attempted to load large shipping racks onto the trailer through the building entranceway, the upper portion of the shipping racks may bump into the rear end of the trailer as a result of the lack of alignment of the upper and lower portions of the trailer side walls. Usually, there is sufficient extra loading space in the trailer so that if the fork lift truck is moved into adjusted alignment with the rear entranceway of the trailer, cargo may be loaded or unloaded without interference.
In the past, the fork lift operator has overcome this problem by manipulating the fork lift truck and cargo racks left or right to positions where loading and unloading may be accomplished. However, a modern innovation in this area has resulted in providing automated fork lift trucks to accomplish the loading and unloading functions without the necessity of a human operator. Such a system is described in my co-pending U.S. patent application Ser. No. 375,084, filed July 3, 1989, now U.S. Pat. No. 4,968,209. The fork lift truck is guided in a predetermined path which assumes that the side walls of the highway trailer are in vertical alignment. When such is not the case, there is no means for the electronic guide system to accommodate the variance.
As a consequence, a highway trailer entry guide is provided in accordance with the present invention. This guide will force the fork lift truck, normally by impinging against the cargo rack, to alter its course when the rear of a highway trailer is misaligned, whether such misalignment is caused by parking or by tilted side walls. It is only necessary to shift the path of the fork lift truck a small distance in order to accomplish the desired loading. The entry guide of the present invention will work with a standard fork lift truck. However, a fork lift truck having the ability to permit shifting of the cargo sideways when the cargo is laterally impacted, such as is disclosed in my above-identified application, is preferred.